Por mucho que cambie el criterio de evaluación, lo usamos.

It is a concessive expression. It introduces the idea of no matter how much or however much something happens.

So por mucho que cambie el criterio de evaluación means something like:

• no matter how much the assessment criterion changes
• however much the assessment criterion changes

The main idea is: even if there are changes, the action in the main clause still happens.

Because por mucho que normally triggers the subjunctive.

This happens because the speaker is not talking about one specific, factual change as a simple event. Instead, they are presenting the change as a possible, variable, or indefinite circumstance that does not affect the main result.

So:

• Por mucho que cambie... = No matter how much it may change...

This kind of concessive idea very often uses the subjunctive in Spanish.

Using cambia would sound wrong in standard Spanish in this structure.

After por mucho que, Spanish expects the subjunctive:

• por mucho que cambie
• not por mucho que cambia

The reason is grammatical, not just stylistic: por mucho que sets up a concession with an uncertain, open, or irrelevant condition, and that is exactly the kind of context where Spanish uses the subjunctive.

The subject is el criterio de evaluación.

So the structure is:

• el criterio de evaluación = the thing doing the changing
• cambie = changes

In other words, the assessment criterion changes.

This use of cambiar is intransitive here: the criterion itself changes.

Lo is a direct object pronoun meaning it.

In context, it refers to a masculine singular thing already known from the conversation or from the wider context. Grammatically, it could refer to el criterio de evaluación, since that noun is masculine singular.

So:

• lo usamos = we use it

A learner should know, though, that pronouns like lo often depend on context. If this sentence appeared by itself, a native speaker might still wonder exactly what lo refers to unless it had already been established.

Because usar normally takes a direct object, not an indirect object.

So for it, Spanish uses:

• lo for a masculine singular direct object
• la for a feminine singular direct object

Since criterio is masculine, the pronoun is lo.

So:

• Usamos el criterio → Lo usamos

Using le here would not be standard for most learners of Spanish.

Because mucho is the correct word in this fixed structure: por mucho que.

Here mucho expresses quantity or degree: however much.

You cannot say:

• por muy que cambie ❌

But you can say:

• por mucho que cambie ✅

There is also a different pattern with muy before adjectives or adverbs, for example:

• por muy difícil que sea = no matter how difficult it is

So:

• por mucho que + verb
• por muy + adjective/adverb + que + verb

Yes, very much so.

It is a common Spanish pattern used to express concession. You can think of it as a set phrase.

Other similar concessive expressions are:

• por más que
• aunque
• aun si

But por mucho que has a very specific sense of no matter how much.

Yes, in many contexts you can.

• Por mucho que cambie el criterio de evaluación, lo usamos.
• Por más que cambie el criterio de evaluación, lo usamos.

Both are possible and both introduce a concessive idea.

That said, there can be slight differences in tone depending on region and context. In many cases, por más que is extremely common and may sound a little more natural to some speakers.

Sometimes, yes, but it is not exactly the same.

• Aunque cambie el criterio de evaluación, lo usamos = Even if the assessment criterion changes, we use it
• Por mucho que cambie el criterio de evaluación, lo usamos = No matter how much the assessment criterion changes, we use it

So aunque gives a more general even if / although idea, while por mucho que stresses degree: the amount of change does not matter.

Because the subordinate clause comes first:

• Por mucho que cambie el criterio de evaluación, lo usamos.

In Spanish, when a subordinate clause is placed before the main clause, a comma is normally used to separate them.

So the comma helps show the structure clearly:

1. concessive subordinate clause
2. main clause

Yes. You could also put the main clause first:

• Lo usamos, por mucho que cambie el criterio de evaluación.

That is also grammatical.

The version with the concessive clause first is often used to foreground the idea of concession: regardless of the changes...

It is grammatically fine, but on its own it may feel a little context-dependent.

That is mainly because of lo:

• lo usamos = we use it

A listener will usually expect to know what it refers to already.

Also, if lo refers to el criterio de evaluación, the sentence means that even though the assessment criterion changes, we still use it. That is possible, but it depends on the situation being discussed.

So the grammar is clear, but the sentence works best when there is some context.

Usamos is the present indicative of usar.

It is indicative because this is the main statement the speaker is asserting as real:

• lo usamos = we use it

So the contrast is:

• cambie = subjunctive, because it is in a concessive clause introduced by por mucho que
• usamos = indicative, because it states the main fact

This contrast between subjunctive in the subordinate clause and indicative in the main clause is very common in Spanish.